Android开发检测App从后台进入前台的解决方法

public class ActLifecycle implements ActivityLifecycleCallbacks {

  private int mPreActivityStartedCount = 0;
  private int mActivityStartedCount = 0;
  private int mActivityOrientation = Configuration.ORIENTATION_UNDEFINED;

  @Override
  public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
  }

  @Override
  public void onActivityStarted(Activity activity) {
    mPreActivityStartedCount = mActivityStartedCount;
    mActivityStartedCount++;
    int orientation = getOrientation(activity);
    if (mPreActivityStartedCount == 0 && mActivityStartedCount == 1
        && orientation == mActivityOrientation) {
      handleAppForeground(activity);//app从后台进入前台了，在这个自定义的方法里处理具体的业务
    }
    mActivityOrientation = orientation;
  }

  private int getOrientation(Activity activity) {
    if (activity != null && activity.getResources() != null) {
      Configuration configuration = activity.getResources().getConfiguration();
      if (configuration != null) {
        return configuration.orientation;
      }
    }
    return Configuration.ORIENTATION_UNDEFINED;
  }

  @Override
  public void onActivityResumed(Activity activity) {
  }

  @Override
  public void onActivityPaused(Activity activity) {
  }

  @Override
  public void onActivityStopped(Activity activity) {
    mPreActivityStartedCount = mActivityStartedCount;
    mActivityStartedCount--;
  }

  @Override
  public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
  }

  @Override
  public void onActivityDestroyed(Activity activity) {
  }
}

//注册app生命周期回调函数

application.registerActivityLifecycleCallbacks(new ActLifecycle());